1. Field of the Invention
This invention relates generally to vertically adjustable swivel chairs, and more particularly to a support spindle assembly for such chairs.
2. Description of the Prior Art
Swivel chairs are well known and widely used. Early swivel chairs included a screw secured to either the seat or base and useful to adjust the height by turning the screw or nut. However, the chairs could not be swiveled without changing the chair height. The latter problem was subsequently dealt with by a separate collar or, handwheel or knob (as in U.S. Pat. No. 2,219,814, for example).
Another type of swivel chair known to us, had the capability of height adjustment without the use of a screw. Such chairs used various types of sleeves and clutching means to permit height adjustment, while the chair could be swiveled without it affecting the height at all. Examples are shown in U.S. Pat. Nos. 2,338,783 and 2,469,896.
A further type of vertically adjustable swivel chairs employs fluids therein for height adjustment. An example is shown in U.S. Pat. No. 2,505,100. Some of these have an advantage over the types mentioned above, in the respect that they may be useful to provide some cushioning under seating loads.
The above mentioned types of adjustable spindles have some disadvantages. The first mentioned type, although simple in construction, provides no cushioning and produces a change of height during swiveling while the seat is occupied. If the change is so little as not to be noticable, then it takes too many turns to obtain a change of height, when it is desired. If the screw is such that the height change will be noticed, then the swiveling is either going to be less free than desired, or the height change will be objectionable.
In the type using the clutching device, there is considerable complexity, as well as the necessity for understanding the mechanism in order to obtain the desired height adjustment. For example, at least one such device requires that the chair be pulled to maximum height, before it can be lowered. Then it must be lowered all the way before it can be locked at any desired height upon raising it again.
The fluid operated height adjustment involves some complexity and expense, plus the necessity for adequate and secure valving and sealing of the fluids employed.
The present invention is addressed to solving a continuing need for a swivel chair column assembly in which height adjustment can be readily secured, swiveling can be readily achieved without a change of height when the seat is occupied, and cushioning of seating loads is also provided, in a comparatively simple and inexpensive assembly.